This disclosure is generally related photoresist removal, and, more particularly, is related to gas-expanded liquids, methods of use thereof, and systems of using gas-expanded liquids.
Photoresist removal is one of the most critical and most repeated cleaning processes in the fabrication of an integrated circuit (IC). Fabrication of a state-of-the-art ICs includes the use of over twenty-five masking steps, each utilizing a photoresist for pattern generation, and each requiring a subsequent photoresist removal process. Photoresist exposed to processes such as ion implantation and plasma reactive ion etching becomes a heavily carbonized, hardened polymeric residue that can be particularly difficult to remove. Current commercial chemical formulations can be ineffective in removing these etch residues.
Commercial liquids range from organic to aqueous and acidic to basic, but they often share the common property of being environmentally hazardous with regard to flammability, human health, and pollution. In addition, limitations may exist in using liquids to process nanoscale features. For instance, viscosity, surface tension, and diffusivity of liquids may inhibit mass transport and surface wetting. Supercritical and liquid carbon dioxide (CO2) has been proposed as alternatives to conventional liquids, but these are limited by the high pressures required in these systems, which must be at least the vapor pressure of CO2 for liquid-phase operation and, in some cases, up to several thousand pounds per square inch (psi) for supercritical fluids.
Thus, a heretofore unaddressed need exists in the industry to address the aforementioned deficiencies and/or inadequacies.
Briefly described, embodiments of this disclosure, among others, include gas-expanded liquids, methods of use thereof, and systems of using gas-expanded liquids. One exemplary system, among others, includes: a gas-expanded liquid system comprising a gas and a liquid, wherein the gas-expanded liquid system is adapted to generate a gas-expanded liquid; and a substrate handling system adapted to position a substrate having a photoresist layer so that the gas-expanded liquid can be made to contact the substrate to remove the photoresist layer.
An exemplary method of cleaning a substrate, among others, includes: providing the substrate having a photoresist layer disposed thereon; exposing at least a portion of the substrate to a gas-expanded liquid; and removing the photoresist layer from the exposed area of the substrate.